Connecticut-based online pharmacy Valisure has petitioned the FDA to recall specific batches of the type 2 diabetes drug metformin from numerous manufacturers because it found high levels of N-Nitrosodimethylamine (NDMA) in the products.

In a citizen petition, the online pharmacy said it found 16 batches out of 38 tested to have NDMA levels above the FDA’s acceptable 96 nanograms daily intake limit.

In its own testing, Valisure said it found specific batches from Amneal Pharmaceuticals and Ascend Laboratories with more than 10 times the acceptable limit. But other companies —including Actavis, Apotex, Aurobindo and Time Cap Laboratories — had products with levels of NDMA above the 96 ng limit.

The FDA ruled out recalls after it found no metformin products that exceeded the daily intake limits for NDMA. The agency tested 16 lots from seven different drugmakers but not Amneal or Ascend.